Fence extension - Metal posts

[elviLan]

Hello, I want to extend the height of my fence with a privacy trellis, but I’m not sure what is the best way to go about it.
I want to extend 5 of my fence panels, each of them measuring currently 114cm x 183cm. I’d like to add a trellis on top of each panel, ideally measuring at least 60cm, just to have a bit more privacy in the garden.
The issue is, the fence post are not your typical ones, but they square, hollow and made of metal, and the existing panels have just been nailed to them (so there’s so gap on the post to slot in anything).
Another issue is that the garden is on a slight slope, so the panels/posts are not precisely levelled.
I’m attaching few pictures so it’s clearer.
Does anyone have any tips on how to extend the posts and attach my trellis? Is it even possible at all?
Thanks in advance for any help!!

 

[jj4091]

Is it your fence or neighbours and do you nned planning permision to go that much higher

 

[accelerator]

Here is a suggestion ... it is not necessarily a good idea!

You could drop down higher square profile timber posts into the current hollow posts and secure them (screws or glue). You could then run a top bar between the new higher posts, and you could secure your trellis to that, plus the top of the existing fence.

Remember though you will be adding weight and more wind resistance for the existing fence posts to cope with, so they would need to be in the ground securely.

Also, how have they managed to nail the fence panels into metal?

 

[Why Not Indeed]

Dropping something into the existing posts sounds like a winner.